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/*
 *      ADM5120_WDT 0.01: Infineon ADM5120 SoC watchdog driver
 *      Copyright (c) Ondrej Zajicek <santiago@crfreenet.org>, 2007
 *
 *      based on
 *
 *      RC32434_WDT 0.01: IDT Interprise 79RC32434 watchdog driver
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 *
 */
#include <linux/module.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/irq.h>

#include <asm/bootinfo.h>

#include <asm/mach-adm5120/adm5120_info.h>
#include <asm/mach-adm5120/adm5120_defs.h>
#include <asm/mach-adm5120/adm5120_switch.h>

#define DEFAULT_TIMEOUT 15              /* (secs) Default is 15 seconds */
#define MAX_TIMEOUT     327
/* Max is 327 seconds, counter is 15-bit integer, step is 10 ms */

#define NAME "adm5120_wdt"
#define VERSION "0.1"

static int expect_close;
static int access;
static unsigned int timeout = DEFAULT_TIMEOUT;

static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
MODULE_LICENSE("GPL");


static inline void wdt_set_timeout(void)
{
        u32 val = (1 << 31) | (((timeout * 100) & 0x7FFF) << 16);
        SW_WRITE_REG(SWITCH_REG_WDOG0, val);
}

/*
   It looks like WDOG0-register-write don't modify counter,
   but WDOG0-register-read resets counter.
*/

static inline void wdt_reset_counter(void)
{
        SW_READ_REG(SWITCH_REG_WDOG0);
}

static inline void wdt_disable(void)
{
        SW_WRITE_REG(SWITCH_REG_WDOG0, 0x7FFF0000);
}



static int wdt_open(struct inode *inode, struct file *file)
{
        /* Allow only one person to hold it open */
        if (access)
                return -EBUSY;

        if (nowayout)
                __module_get(THIS_MODULE);

        /* Activate timer */
        wdt_reset_counter();
        wdt_set_timeout();
        printk(KERN_INFO NAME ": enabling watchdog timer\n");
        access = 1;
        return 0;
}

static int wdt_release(struct inode *inode, struct file *file)
{
        /*
         * Shut off the timer.
         * Lock it in if it's a module and we set nowayout
         */
        if (expect_close && (nowayout == 0)) {
                wdt_disable();
                printk(KERN_INFO NAME ": disabling watchdog timer\n");
                module_put(THIS_MODULE);
        } else
                printk(KERN_CRIT NAME ": device closed unexpectedly.  WDT will not stop!\n");

        access = 0;
        return 0;
}

static ssize_t wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
{
        /* Refresh the timer. */
        if (len) {
                if (!nowayout) {
                        size_t i;

                        /* In case it was set long ago */
                        expect_close = 0;

                        for (i = 0; i != len; i++) {
                                char c;
                                if (get_user(c, data + i))
                                        return -EFAULT;
                                if (c == 'V')
                                        expect_close = 1;
                        }
                }
                wdt_reset_counter();
                return len;
        }
        return 0;
}

static long wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        int new_timeout;
        static struct watchdog_info ident = {
                .options =              WDIOF_SETTIMEOUT |
                                        WDIOF_KEEPALIVEPING |
                                        WDIOF_MAGICCLOSE,
                .firmware_version =     0,
                .identity =             "ADM5120_WDT Watchdog",
        };
        switch (cmd) {
        default:
                return -ENOTTY;
        case WDIOC_GETSUPPORT:
                if (copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)))
                        return -EFAULT;
                return 0;
        case WDIOC_GETSTATUS:
        case WDIOC_GETBOOTSTATUS:
                return put_user(0, (int *)arg);
        case WDIOC_KEEPALIVE:
                wdt_reset_counter();
                return 0;
        case WDIOC_SETTIMEOUT:
                if (get_user(new_timeout, (int *)arg))
                        return -EFAULT;
                if (new_timeout < 1)
                        return -EINVAL;
                if (new_timeout > MAX_TIMEOUT)
                        return -EINVAL;
                timeout = new_timeout;
                wdt_set_timeout();
                /* Fall */
        case WDIOC_GETTIMEOUT:
                return put_user(timeout, (int *)arg);
        }
}

static const struct file_operations wdt_fops = {
        .owner          = THIS_MODULE,
        .llseek         = no_llseek,
        .write          = wdt_write,
        .unlocked_ioctl = wdt_ioctl,
        .open           = wdt_open,
        .release        = wdt_release,
};

static struct miscdevice wdt_miscdev = {
        .minor          = WATCHDOG_MINOR,
        .name           = "watchdog",
        .fops           = &wdt_fops,
};

static char banner[] __initdata = KERN_INFO NAME ": Watchdog Timer version " VERSION "\n";

static int __init watchdog_init(void)
{
        int ret;

        ret = misc_register(&wdt_miscdev);

        if (ret)
                return ret;

        wdt_disable();
        printk(banner);

        return 0;
}

static void __exit watchdog_exit(void)
{
        misc_deregister(&wdt_miscdev);
}

module_init(watchdog_init);
module_exit(watchdog_exit);